Lubricant containing mixture of low and high molecular weight sulfonates



US. Cl. 252-33 6 Claims ABSTRACT F THE DISCLOSURE Anti-rust andcleanliness properties of lubricating oils are improved by the additionof a blend of high and low molecular weight highly basic alkaline-earthmetal petroleum sulfonates.

This invention relates to lubricating compositions, and particularly tolubricating compositions containing a highly basic alkaline earth metalsulfonate additive which imparts good anti-rust and cleanlinessproperties thereto.

It is known that basic calcium sulfonates are useful components oflubricants for internal combustion engines. These sulfonates containexcess base which imparts alkaline reserve to the lubricant, thealkaline reserve neutralizes sulfur and acids during application of thelubricant. Sulfonates of this type which have a molecular weight ofabout 470 are good rust inhibitors, but they promote low temperaturesludging characteristics of the lubricant. The higher molecular weightsulfonates of this type do not'promote low temperature sludging, but theanti-rust activity thereof is not acceptable.

It has now been found in accordance with the present invention that aninternal combustion engine lubricant containing an oil-soluble additiveconsisting essentially of a blend or mixture of (1) low molecular weightand (2) high molecular weight, highly basic, alkaline earth metalsulfonates possesses good anti-rust activity without promotingundesirable characteristics, such as the expected low temperaturesludging characteristics.

The sulfonates may be either synthetic or petroleum sulfonates. Theterms petroleum sulfonate or petro leum sulfonic acids as used in thisspecification are intended to cover all sulfonates or sulfonic acidswhich are derived directly from petroleum products, such as lubricatingoils. The term synthetic sulfonate is intended to include all sulfonateswhich are not petroleum sulfonates. By basic sulfonate is meant that theend product contains excess base and has a basicity of at least 20% andup to 1000% or more. Basicity of the subject sulfonates is usuallydefined as the excess of metal in the sulfonate over that quantity ofmetal which would be present in the normal (non-basic) sulfonate. Theexcess base appears to be present in the sulfonate in the form of theoriginal base used to neutralize the acid. Thus, if the content of metalin a particular sulfonate mixture is (a) percent by weight, and if thecontent of metal the mixture would have if it were present only as thenormal nited States Patent 0 3,480,550 Patented Nov. 25, 1969 sulfonateis (b) percent by weight, then the basicity of the mixture is (b) X100%it can also be expressed as percent basicity=moles [CaCO -I-Ca (0H)z] X100/moles Ca(SO R) The low molecular weight sulfonate component of theadditive has an average equivalent weight of from about 450 to 550, andmay be a petroleum sulfonate prepared from LVI, MVI or HVI neutrallubricating oils of a synthetic sulfonate. As used herein, VI representsviscosity index and L, M and H represent low, medium and high. The termequivalent weight as used herein has its usual meaning, i.e., theequivalent of a substance in grams, which is calculated by dividing itsformula weight (molecular weight) by the valence of its metal atom. Forexample, the equivalent Weight of a calcium sulfonate is one-half itsmolecular weight, whereas the molecular weight and equivalent Weight ofa sodium sulfonate are the same. Accordingly, calcium sulfonates areoften classified by their equivalent weight which is approximately 'thesame as the equivalent weight or molecular weight of the correspondingsodium sulfonate.

The neutral oils which may be used to prepare a low molecular weightpetroleum sulfonate may be obtained from a variety of natural oils suchas parafiinic, naphthenic and mixed base crudes. Preferably, the neutraloils for use in preparing the low molecular weight petroleum sulfonatesare LVI, MVI and HVI neutrals having viscosities of from 100 to 2000 SSUat 100 F. and average molecular weights of from 250 to 500. Examples ofsuitable neutral oils include oils having the following properties:

TABLE 1 Property A B O D E Gravity, API 24. 7 21. 7 22. 8 22. 5 30. 0Color, ASTM L1. 5 L2. 5 l. 5 2.0 L1. 6 Pour Point, F 0 0 40 20 10 Flash000 F 480 440 325 415 430 Fire, F 540 500 360 455 500 Viscosity:

SSU at 100 F 1 250 1, 080 106 557 265 SSU at; 210 F 82. 5 71. 2 38. 255. 8 50 Viscosity Index" 55. 0 25 t 25 93 Neutral,TBN-E AcidNeutralization Numben 0. 025 0. 03 0. 03 O. 1

1 Neutral.

The ratio of the low molecular weight sulfonate component of theadditive to the high molecular component is from 0121.0 to 03:10

The high molecular weight sulfonate component of the additive has anaverage equivalent weight of at least 700, and preferably from 725 to900, and may be a petroleum sulfonate prepared from bright stock or asynthetic sulfonate.

Bright stock oil fraction is a viscous product refined by solventextraction, hydrotreated, and then dewaxed. The viscosity of the brightstocks vary from about to 250 SSU at 210 F. Bright stock used to preparethe additive of the present invention has an average molecular weightrange of from about 650 to 900, or higher.

The high and low molecular weight petroleum sulfonates which may be usedin forming the additive are conveniently prepared by (1) sulfonation ofthe base stock with a sulfonating agent, such as sulfur trioxide,chlorosulfonic acid or oleum (fuming sulfuric acid) and preferably thesulfonating agent is fuming sulfuric acid; (2) separation of thesulfonic acid; (3) neutralization of the acid with a hydroxide, such ascalcium or sodium, prefreably calcium, to yield a slightly basicsulfonate; and finally (4) carbonation of the sulfonate in the presenceof excess of an alkaline earth metal hydroxide, such as barium orcalcium hydroxide, to yield the highly basic alkaline earth metalpetroleum sulfonate.

The high and low molecular weight synthetic sulfonates which may be usedin forming the additive include those described in US. Patent No.3,250,710 and Canadian Patent No. 733,142. Thus, the oil-solublesynthetic sulfonates, such as calcium sulfonates, can be of the cyclicor aliphatic type. The cyclic sulfonates include the monoor poly-nucleararomatic or cycloaliphatic sulfonates. The synthetic sulfonates can berepresented by the following formulas:

3)a]d b wherein M is calcium, T is a cyclic nucleus such as, forexample, benzene, naphthalene, enthracene, phenanthrene, diphenyleneoxide, thianthrene, phenothioxine, diphenylene sulfide, phenothiazine,diphenyl oxide, diphenyl sulfide, diphenylamine, cyclohexene, petroleumnaphthenes, decahydronaphthalene, cyclopentane, etc.; R is an aliphaticgroup such as alkyl, alkenyl, alkoxy, alkoxyalkyl, carboalkoxyalkyl,etc.; x is at least 1, and R,,T contains a total of at least about 15carbon atoms. R is an aliphtic radical containing at least about 15carbon atoms. Examples of types of the R radical are alkyl, alkenyl,alkoxyalkyl, carboalkoxyalkyl, etc. Specific examples of R are saturatedand unsaturated paratfin wax, and polyolefins, including polymerized C CC C C etc., olefins having molecular weights from 200 to 1000. Thegroups T, R, and R in the above formulas can also contain otherinorganic or organic substituents in addition to those enumerated abovesuch as, for example, hydroxy, mercapto, halogen, nitro, amino, nitroso,sulfides, disulfide, etc. In the above formulas y, z, a, b and d arealso at least 1.

Specific examples of oil-soluble synthetic sulfonates are the calciumsalts of monoand polywax substituted sulfonic and polysulfonic acids of,e.g., naphthalene, phenol, diphenyl ether, naphthalene disulfide,dipenylamine, thiophene, alpha-chloronaphthalene, etc.; othersubstituted sulfonic acids such as cetyl chlorobenzene sulfonic acids,cetylphenol mono-sulfide sulfonic acids, cetoxy caprylbenzene sulfonicacids, dicetyl thianthrene disulfonic acids, dilauryl beta-naphthylsulfonic acids, dicapyryl nitronaphthalene sulfonic acids, and alkarylsulfonic acids such as dodecyl benzene bottoms sulfonic acids (i.e.,those acids derived from benzene which has been alkylated with propylenetetramers or isobutene trimers to introduce 1, 2, 3, or morebranched-chain C substituents on the benzene ring. Dodecyl benzenebottoms, principally mixtures of monoand di-dodecyl benzenes, areavailable as byproducts from the manufacture of household detergents)and monoand poly-tridecyl benzenes; aliphatic sulfonic acids such asparaflin wax sulfonic acid, unsaturated paraffin wax sulfonic acids,hydroxy-substituted paraflin wax sulfonic acids, hexapropylene sulfonicacids, tetraamylene sulfonic acids, nitro-paraflin wax sulfonic acids,etc.; cycloaliphatic sulfonic acids such as petroleum naphthene sulfonicacids, cetyl cyclopentyl sulfonic acids, lauryl cyclohexyl sulfonicacids, bis (diisobutyl)cyclohexyl sulfonic acids, mono or poly-waxsubstituted cyclohexyl sulfonic acids, etc. The synthetic sulfonates arethen carbonated in the same manner as the petroluem sulfonates.

Examples I and II are illustrative of a method of preparing the subjectsulfonates.

EXAMPLE I Procedure Ia A high molecular weight petroleum sulfonate wasprepared by charging a 3-liter, Z-necked round-bottom flask equippedwith stirrer, dropping funnel, thermometer and vent with 1 kg. WestTexas Ellenburger bright stock (hereinafter referred to as oil F) havingthe following properties:

Viscosity at F., SSU 2812 Viscosity at 210 F., SSU 116.1 Viscosity index99 Sulfur, percent by weight 0.07 Molecular weight 770 Total aromatics,percent by weight 40 Monoaromatics, percent by weight 28.1

The stock was stirred vigorously and percent by Weight sulfuric acid(200 g., 20 percent by weight oleum) was added dropwise during one hour;the temperature rose from 25 to 45 C. The mixture was stirred anadditional 30 minutes and then 15 ml. of water was added with stirring.The mixture was diluted with a volume of hexane equal to the volumebright stock charged (1132 ml.) and allowed to stand overnight. A smallamount of spent acid (86 ml., 149 g.) separated which was dark brown,quite fluid and easily handled. The hexane layer was washed with asolution of 500- ml. of Water and 750 ml. methanol. The clear yellowlower layer that separated was discarded. The upper layers was shakenwith 750 ml. absolute methanol. Two phases formed and separatedcompletely in two hours. The lower sulfonic acid layers was withdrawn,diluted with 1 liter of n-hexane and shaken with a solution of 68 g. ofsodium hydroxide in 500 ml. water. The two phases were separated. Theaqueous phase was discarded and the hexane layer was stripped of solventand water with nitrogen under vacuum. The residue which was sodiumsulfonate concentrate weighed 520 g.

550 g. of sodium sulfonate prepared by the procedure just described wasstirred with a solution of 700' g. of calcium chloride and 100 g. ofcalcium hydroxide in 2270 ml. water for 4 hours at about 90 C. 10 kg.toluene was added and the water was removed by azeotropic distillationusing a Water trap. The mixture was cooled to 55 C. and a mixture of 294g. calcium hydroxide, 4.4 g. benzoic acid and 1050 g. methanol was addedthereto. The resulting mixture was stirred at 55 C. while 88 g. carbondioxide was bubbled in. The solvents were stripped off and the mixturewas filtered. The product was a highly basic Ca petroleum sulfonate(hereinafter referred to as sulfonate FF) having an average equivalentweight of 750, a 8.3% sulfated ash content and a TBN-E (total basenumber) of 45.6.

Procedure Ib Alternatively, the sulfonic acid layer, present afterextraction with 7 50 ml. of absolute methanol in Procedure Ia, can beneutralized with calcium hydroxide in aqueous slurry by stirring with250 ml. water and 74 g. calcium hydroxide for 5 minutes, separating theneutralized product and treating as before with calcium hydroxide,benzoic acid, methanol and carbon dioxide.

The following examples are for purposes of illustrating the inventionand are not intended to limit the invention to the particular compoundsand compositions described.

EXAMPLE II The procedure of Example Ia was repeated with the exceptionthat 1 kg. of an LVI 60/210 neutral oil, designated hereinbefore as oilD in Table 1, was used as the sulfonate feed in place of the brightstock of Example Ia. The resulting highly basic Ca petroleum sulfonate(sulfonate DD) had an average equivalent weight of 470. Similarly,highly basic sulfonates AA, BB, CC and BB were also prepared from oilsA, B, C and E of Table 1, respectively.

EXAMPLE 111 This example illustrates the influence of sulfonatemolecular weight on rust protection as determined in the severe FalconEngine Rust Tests. This test is described in detail in Ghanuams SAEPaper No. 650,869, presented at Tulsa, Okla., Nov. 2-4, 1965 meeting.The results of the test are given in Table 2.

Percent by wt. Sulfonate (sulfated ash) 1.2 Polyisobutenylsuccinimide oftetraethylene pentamme Zinc bis(octylphenyl)dithiophosphate 3.4 SAE 10Wmotor oil Balanc The results of the test are given in Table 3.

TABLE 3.SEQ,UENCE V CLEANLINESS TEST D D (tail) 1 E A 13 FordSulfonation feed, sulfonate mol. wt. Requlre- Seq. V Cleanliness Ratingment 470 480 504 540 720 Overall sludge (50=clean) 26. 5 34. 9 38. 8 42.3 48. 7 Piston lacquer (10=clean) 7 7. 0 8.2 8. 2 9. 0 9. 7 Overalllacquer (50=clean) 27. 0 38. 5 42. 3 44. 8 48. 6 O l screen plugging,percent. 30 90 5 1 5 1 011 ring plugging, percent 30 60 61 2 2 0 1 D(tail) is oil D which has been topped to remove some of the lighterends, thereby increasing the average molecular weight of the oil.

TABLE 2.FALCON-ENGINE RUST TEST Oil Sulionation Feed D A F Sulfonateequivalent wt 470 640 750 Formulation, Percent w.:

Sulfonate, percent w. suliated ash.-." 1. 2 1. 2 1. 2 succinimide 1 1.0 1. 0 l. 0 Sine dithiophosphatekn 3. 4 3. 4 3. 4 Acrylo' 150 3 0. 5 0.5 0. 5 Balance mineral oil- Rust Rating (l0=no rus Valve lifters 9. 8 9.0 7. 0 Overall 9. 8 8. 9 7. 5

1 Polyisobutenyl succinimide of tetraethylene pentamine. 2 Sinebis(octylphenyl) dithiophosphate. 3 Methacrylate polymer.

The data of Table 2 show that as the molecular weight of the sulfonatesincrease the rust protection afforded thereby decreases.

Although the rust protection provided by the low molecular weightsulfonate is acceptable, the cleanliness provided thereby is not good.Cleanliness properties of formulations containing sulfonates of variousmolecular weights is illustrated in Example IV.

EXAMPLE IV This example illustrates the influence of sulfonate molecularweight on engine cleanliness as determined by MS Sequence V Engine Testwhich was designed to evaluate engine deposits produced by low andmedium temperature operating conditions with emphasis on antisludging,anti-clogging, and insoluble suspension characteristics of enginelubricants. The test engine is a 368 cu. in. Lincoln; the test fuel is aconventional summer grade regular gasoline. The test conditions are ingeneral:

[Duration-192 hrs. (48 cycles, 4 hrs.)]

Speed, Water, Oil, Time Load r.p.m. F. F. Air/fuel None 500 115 125 9.5(rich). Approx. 2, 500 125 175 15.5 (lean). Approx. 36.... 2, 500 170205 15.5 (lean).

After 48 cycles without oil drain, the engine is disassembled andinspected. Sulfonates EE, FF, BB and GG were evaluated in the Sequence VTest at a 1.2 percent by weight sulfated ash level and using an oil ofthe following formulation:

EXAMPLE V A blend of sulfonates DD and FF (blend DF) was preparedwhereby the blend had a sulfated ash level of 1.2 percent by weight ofwhich sulfonate DD provided 0.2% thereof and sulfonate FF provided 1.0percent by weight. The sulfonate blend was incorporated into aformulation for purposes of comparing its performance in the Falcon RustTest and the Sequence V Test, respectively, with the sulfonatespreviously tested therein.

Formulation X Blend DF, percent by weight sulfated ash 1.2Polyisobutenyl succinimide of tetraethylene pentamine None Zincbis(octylphenyl)dithiophosphate 3.4 Acryloid 0.5 Mineral oil BalanceFormulation X is the same as the formulations used in the previousFalcon Rust Test (Example III) and Sequence V Test (Example IV) with theexception of the particular sulfonates and that Formulation X does notcontain the succinimide (dispersant).

The results of these tests are given in Table 4.

TABLE 4 Sequence V Engine Tests Seq. V ratings: Formulation X Overallsludge, 50:clean 47.2 Overall lacquer, 50=clean 47.5 Oil ring clogging,percent 0 Oil screen clogging, percent 1 Falcon-Rust Engine Tests Rustrating, l0=no rust: Formulation X Valve lifters 9.7 Overall 9.3

The data of Table 4 establish that blend DF provides both good enginerust protection and good engine cleanliness, whereas the individualsulfonates at the same sulfated ash level provide either good rustprotection or good cleanliness, but not both. This result is unexpectedat the concentrations of the individual sulfonates comprising theadditive, since it would be expected that a higher concentration of thelow molecular weight sulfonate would be required to afford adequate rustprotection. The benefit of the necessity of using only a small amount ofthe low molecular weight sulfonate in the blend is that greatercleanliness can be attained, owing to the higher concentration of thehigh molecular weight sulfonate on the one hand and the lowerconcentration of the low molecular weight sulfonate on the other hand.Moreover, the sulfonate blend also has good dispersancy properties asdemonstrated in Table 4, Formulation X.

EXAMPLE VI A blend of synthetic sulfonates is prepared from (1)carbonated calcium sulfonate of postdodecylbenzene (constitutes amixture of dodecylbenzene and didodecylbenzene in approximate molarratio of 2.3) and (2) carbonated calcium sulfonate of polyisobutenesulfonic acids having an average equivalent weight of about 750, whereinthe blend contains (1) and (2) in the weight ratio of 5 to 1. Aformulation is then prepared containing 97% by weight of mineral oil and3% by weight of the blend.

The sulfonate blend of the present invention may be incorporated intomineral lubricating oil obtained from paraffinic, asphaltic or mixedbase crudes and/or mixtures thereof, for example, a neutral oil having aviscosity which may vary over a wide range such as from 100 to 2000 SSUat 100 F. Under extreme engine operating conditions it is desirable touse an oil blend containing from 1 to of bright stock having a viscosityof from 80 to 250 SSU at 210 F. and a range in molecular weight fromabout 500 to 2000 or higher. In addition to mineral lubricating oils,the adduct additives may be incorporated into synthetic lubricating oilssuch as polymerized olefins, esters and others. Mixtures of natural andsynthetics can also be used.

The additives of this invention can be used effectively in any of theabove oily media in amounts of from 0.1% to 20% by weight and preferablyfrom 2% to 13% although amounts as large' as or as little as 0.01% byweight may effectively be incorporated into oils under certaincircumstances.

Other additives may also be incorporated into lubricating compositionsin addition to the sulfonate blend of the present invention such as anyof the additives recognized in the art to perform a particular functionor functions, i.e., pour point depressants and viscosity indeximprovers, e.g., methacrylate polymers (Acryloid 150); dispersants,e.g., nitrogen-containing compounds such as the polyisobutenylsuccinimide of polyethylenearnine, copolymers of 3 vinyl pyridine withat least one acrylate ester or a vinyl pyrrolidone copolymer;anti-oxidants, e.g., amines, phosphorus or phenolic compounds, i.e.,phenyl-alpha-naphthylamine, zinc dialkyldithiophosphates, or4,4'-methylene-bis(2,6-di-t-butylphenol) anti-foam agents; corrosioninhibitors and the like.

The compoistions described herein can be used as motor oils, gear oilsand in various other applications where cleanliness, rust protection,and detergency are desirable.

We claim as our invention: 1

1. A lubricant consisting essentially of a major amount of a lubricatingoil and a minor amount, sutficient to impart rust inhibition anddetergency, of a blend of low molecular weight and high molecular weighthighly basic alkaline-earth metal petroleum sulfonates wherein:

(1) the petroleum sulfonates have a basicity of at least (2) the lowmolecular weight petroleum sulfonate component of the blend has anaverage equivalent weight of from 450 to 550;

(3) the high molecular weight petroleum sulfonate component of the blendhas an average equivalent weight of from 700 to 900; and

(4) the ratio of the low molecular weight component to the highmolecular weight component is from 0.1-1.0 to 0.3-1.0.

2. A lubricant as defined in claim 1 wherein the sulfonates have abasicity of from 100% to 800% 3. A lubricant as defined in claim 1wherein the alkaline earth metal is calcium.

4. A lubricant as defined in claim 1 wherein the high molecular weightsulfonate is prepared from bright stock having an average molecularweight of from about 650 to about 900.

5. A lubricant as defined in claim 1 wherein the low molecular weightsulfonate is prepared from a lubricating oil which is a neutral oilhaving a viscosity of from about 50 to SSU at 210 F.

6. A lubricant as defined in claim 1 wherein the ratio of low to highmolecular weight sulfonates is about 0.2 to 1.0.

References Cited UNITED STATES PATENTS 2,616,911 11/1952 Asseff et a125233.2 XR 2,856,361 10/1958 Schlicht 252-33 2,947,694 8/1960 Gragson252-33 3,242,080 3/1966 Wiley et al. 252-33 3,282,835 11/1966 Asseff252-33 XR DANIEL E. WYMAN, Primary Examiner I. VAUGHN, AssistantExaminer US. Cl. X.R. 252387

